A653 SS Grade 50 Class 1

US counterpart of S350GD: 50 ksi (340 MPa) yield, 65 ksi (450 MPa) tensile for Class 1.

SS Grade 50 comes in classes that differ only in tensile strength: Class 1 65 ksi, Class 2 no minimum, Class 3 70 ksi, Class 4 60 ksi (American Steel & Aluminum, from the A653-05 tables). Order the class.

All values

Strength

Yield strength ReH

Upper yield strength guaranteed by the product standard (minimum).

Condition	Value	Evidence
	≥ 340MPa	Corroborated

Tensile strength Rm

Ultimate tensile strength. Product standards give a range or a minimum.

Condition	Value	Evidence
	≥ 450MPa	Single source1

Ductility

Elongation after fracture A

Minimum elongation; depends on gauge length and test direction.

Condition	Value	Evidence
	≥ 12%	Corroborated

Chemical composition

Show on the periodic table

SS Grade 50, heat analysis, % by mass, maximum (Zhongtang)

Element	Applies to	Max %	Evidence
C	all thicknesses	0.23	Single source
Mn	all thicknesses	1.35	Single source
P	all thicknesses	0.035	Single source
S	all thicknesses	0.040	Single source
Si	all thicknesses	0.40	Single source

Listed as equivalent to

S350GD (EN 10346:2015) — Yield 340 MPa (50 ksi), 10 MPa lower; tensile 450 MPa (Class 1), higher. Elongation 12 % on 2 in., not comparable with A80.

Sources here are public pages that reproduce ASTM A653/A653M. For design and acceptance, the standard edition named in your specification and the inspection certificate (EN 10204 3.1) of the delivered product take precedence.